| what are the secondary stars in CVs? |
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A. Mean density of
secondary star
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B. Volume radius of Roche lobe
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C. Kepler's third law
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Combining A, B & C gives: 
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||
|
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Most CVs have 1 < P < 10 h, resulting in 100 <
 2 < 1 g cm-3.
| |
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| Therefore, CV secondary stars should be main-sequence stars with spectral types ranging from early-G to late-M. | |